One feature of Valve games I've always loved (besides the commentary tracks, obv) was how easy it was to get different localizations of their games, as one of my gaming past-times is finding out how my favourite games sound in different languages. Thankfully, they've carried over this feature to Portal 2 and it's become an endless source for amusement for me. For instance, GLADOS somehow sounds even more sinister in French:
Minor niggles: Dubbing's a tiny bit off for some bits. And with my mere three years of high school French, I'm unsure if Wheately voice translates as well as GLADOS and Cave Johnson do.
If you want to try Russian and Deutsch, just right-click Portal 2 in your Steam games list, Properties, then Languages, et voila.